Re: [PATCH v2] net: missing check virtio
On Thu, Jun 13, 2024 at 12:54:48PM +0300, Denis Arefev wrote:
> Two missing check in virtio_net_hdr_to_skb() allowed syzbot
> to crash kernels again
>
> 1. After the skb_segment function the buffer may become non-linear
> (nr_frags != 0), but since the SKBTX_SHARED_FRAG flag is not set anywhere
> the __skb_linearize function will not be executed, then the buffer will
> remain non-linear. Then the condition (offset >= skb_headlen(skb))
> becomes true, which causes WARN_ON_ONCE in skb_checksum_help.
>
> 2. The struct sk_buff and struct virtio_net_hdr members must be
> mathematically related.
> (gso_size) must be greater than (needed) otherwise WARN_ON_ONCE.
> (remainder) must be greater than (needed) otherwise WARN_ON_ONCE.
> (remainder) may be 0 if division is without remainder.
>
> offset+2 (4191) > skb_headlen() (1116)
> WARNING: CPU: 1 PID: 5084 at net/core/dev.c:3303
> skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
> Modules linked in:
> CPU: 1 PID: 5084 Comm: syz-executor336 Not tainted
> 6.7.0-rc3-syzkaller-00014-gdf60cee26a2e #0
> Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google
> 11/10/2023
> RIP: 0010:skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
> Code: 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 52 01 00 00 44 89 e2 2b
> 53 74 4c 89 ee 48 c7 c7 40 57 e9 8b e8 af 8f dd f8 90 <0f> 0b 90 90 e9 87 fe
> ff ff e8 40 0f 6e f9 e9 4b fa ff ff 48 89 ef
> RSP: 0018:c90003a9f338 EFLAGS: 00010286
> RAX: RBX: 888025125780 RCX: 814db209
> RDX: 888015393b80 RSI: 814db216 RDI: 0001
> RBP: 8880251257f4 R08: 0001 R09:
> R10: R11: 0001 R12: 045c
> R13: 105f R14: 8880251257f0 R15: 105d
> FS: 55c24380() GS:8880b990() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: 2000f000 CR3: 23151000 CR4: 003506f0
> DR0: DR1: DR2:
> DR3: DR6: fffe0ff0 DR7: 0400
> Call Trace:
>
> ip_do_fragment+0xa1b/0x18b0 net/ipv4/ip_output.c:777
> ip_fragment.constprop.0+0x161/0x230 net/ipv4/ip_output.c:584
> ip_finish_output_gso net/ipv4/ip_output.c:286 [inline]
> __ip_finish_output net/ipv4/ip_output.c:308 [inline]
> __ip_finish_output+0x49c/0x650 net/ipv4/ip_output.c:295
> ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
> NF_HOOK_COND include/linux/netfilter.h:303 [inline]
> ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
> dst_output include/net/dst.h:451 [inline]
> ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:129
> iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82
> ipip6_tunnel_xmit net/ipv6/sit.c:1034 [inline]
> sit_tunnel_xmit+0xed2/0x28f0 net/ipv6/sit.c:1076
> __netdev_start_xmit include/linux/netdevice.h:4940 [inline]
> netdev_start_xmit include/linux/netdevice.h:4954 [inline]
> xmit_one net/core/dev.c:3545 [inline]
> dev_hard_start_xmit+0x13d/0x6d0 net/core/dev.c:3561
> __dev_queue_xmit+0x7c1/0x3d60 net/core/dev.c:4346
> dev_queue_xmit include/linux/netdevice.h:3134 [inline]
> packet_xmit+0x257/0x380 net/packet/af_packet.c:276
> packet_snd net/packet/af_packet.c:3087 [inline]
> packet_sendmsg+0x24ca/0x5240 net/packet/af_packet.c:3119
> sock_sendmsg_nosec net/socket.c:730 [inline]
> __sock_sendmsg+0xd5/0x180 net/socket.c:745
> __sys_sendto+0x255/0x340 net/socket.c:2190
> __do_sys_sendto net/socket.c:2202 [inline]
> __se_sys_sendto net/socket.c:2198 [inline]
> __x64_sys_sendto+0xe0/0x1b0 net/socket.c:2198
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller
>
> Signed-off-by: Denis Arefev
I suspect it's this one:
Fixes: 0f6925b3e8da ("virtio_net: Do not pull payload in skb->head")
Though if you can test kernel before that to make sure, that
would be nice.
I'm inclined to merge, crashing syzkaller is not nice.
Acked-by: Michael S. Tsirkin
> ---
> V1 -> V2: incorrect type in argument 2
> include/linux/virtio_net.h | 11 +++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 4dfa9b69ca8d..d1d7825318c3 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -56,6 +56,7 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
> unsigned int thlen = 0;
> unsigned int p_off = 0;
> unsigned int ip_proto;
> + u64 ret, remainder, gso_size;
>
> if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
> @@ -98,6 +99,16 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
> *skb,
> u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
>
Re: [PATCH v2] net: missing check virtio
On Thu, Jun 13, 2024 at 12:54:48PM +0300, Denis Arefev wrote:
> Two missing check in virtio_net_hdr_to_skb() allowed syzbot
> to crash kernels again
>
> 1. After the skb_segment function the buffer may become non-linear
> (nr_frags != 0), but since the SKBTX_SHARED_FRAG flag is not set anywhere
> the __skb_linearize function will not be executed, then the buffer will
> remain non-linear. Then the condition (offset >= skb_headlen(skb))
> becomes true, which causes WARN_ON_ONCE in skb_checksum_help.
>
> 2. The struct sk_buff and struct virtio_net_hdr members must be
> mathematically related.
> (gso_size) must be greater than (needed) otherwise WARN_ON_ONCE.
> (remainder) must be greater than (needed) otherwise WARN_ON_ONCE.
> (remainder) may be 0 if division is without remainder.
>
> offset+2 (4191) > skb_headlen() (1116)
> WARNING: CPU: 1 PID: 5084 at net/core/dev.c:3303
> skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
> Modules linked in:
> CPU: 1 PID: 5084 Comm: syz-executor336 Not tainted
> 6.7.0-rc3-syzkaller-00014-gdf60cee26a2e #0
> Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google
> 11/10/2023
> RIP: 0010:skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
> Code: 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 52 01 00 00 44 89 e2 2b
> 53 74 4c 89 ee 48 c7 c7 40 57 e9 8b e8 af 8f dd f8 90 <0f> 0b 90 90 e9 87 fe
> ff ff e8 40 0f 6e f9 e9 4b fa ff ff 48 89 ef
> RSP: 0018:c90003a9f338 EFLAGS: 00010286
> RAX: RBX: 888025125780 RCX: 814db209
> RDX: 888015393b80 RSI: 814db216 RDI: 0001
> RBP: 8880251257f4 R08: 0001 R09:
> R10: R11: 0001 R12: 045c
> R13: 105f R14: 8880251257f0 R15: 105d
> FS: 55c24380() GS:8880b990() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: 2000f000 CR3: 23151000 CR4: 003506f0
> DR0: DR1: DR2:
> DR3: DR6: fffe0ff0 DR7: 0400
> Call Trace:
>
> ip_do_fragment+0xa1b/0x18b0 net/ipv4/ip_output.c:777
> ip_fragment.constprop.0+0x161/0x230 net/ipv4/ip_output.c:584
> ip_finish_output_gso net/ipv4/ip_output.c:286 [inline]
> __ip_finish_output net/ipv4/ip_output.c:308 [inline]
> __ip_finish_output+0x49c/0x650 net/ipv4/ip_output.c:295
> ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
> NF_HOOK_COND include/linux/netfilter.h:303 [inline]
> ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
> dst_output include/net/dst.h:451 [inline]
> ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:129
> iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82
> ipip6_tunnel_xmit net/ipv6/sit.c:1034 [inline]
> sit_tunnel_xmit+0xed2/0x28f0 net/ipv6/sit.c:1076
> __netdev_start_xmit include/linux/netdevice.h:4940 [inline]
> netdev_start_xmit include/linux/netdevice.h:4954 [inline]
> xmit_one net/core/dev.c:3545 [inline]
> dev_hard_start_xmit+0x13d/0x6d0 net/core/dev.c:3561
> __dev_queue_xmit+0x7c1/0x3d60 net/core/dev.c:4346
> dev_queue_xmit include/linux/netdevice.h:3134 [inline]
> packet_xmit+0x257/0x380 net/packet/af_packet.c:276
> packet_snd net/packet/af_packet.c:3087 [inline]
> packet_sendmsg+0x24ca/0x5240 net/packet/af_packet.c:3119
> sock_sendmsg_nosec net/socket.c:730 [inline]
> __sock_sendmsg+0xd5/0x180 net/socket.c:745
> __sys_sendto+0x255/0x340 net/socket.c:2190
> __do_sys_sendto net/socket.c:2202 [inline]
> __se_sys_sendto net/socket.c:2198 [inline]
> __x64_sys_sendto+0xe0/0x1b0 net/socket.c:2198
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
> Found by Linux Verification Center (linuxtesting.org) with Syzkaller
>
> Signed-off-by: Denis Arefev
> ---
> V1 -> V2: incorrect type in argument 2
> include/linux/virtio_net.h | 11 +++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index 4dfa9b69ca8d..d1d7825318c3 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -56,6 +56,7 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
> unsigned int thlen = 0;
> unsigned int p_off = 0;
> unsigned int ip_proto;
> + u64 ret, remainder, gso_size;
>
> if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
> @@ -98,6 +99,16 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
> *skb,
> u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
> u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
>
> + if (hdr->gso_size) {
> + gso_size = __virtio16_to_cpu(little_endian,
> hdr->gso_size);
> + ret = div64_u64_rem(skb->len, gso_size,
Re: [PATCH v2] net: missing check virtio
On Fri, 14 Jun 2024 13:18:26 +0300 Denis Arefev wrote: > Yeah, I was thinking of adding Fixes: > > But this code is new, it complements what is done. > 1. check (!(ret && (hdr->gso_size > needed) && >((remainder > needed) || (remainder == 0 > complements comit 0f6925b3e8da0 > > 2. The setting of the SKBFL_SHARED_FRAG flag can be associated with this > comit cef401de7be8c. > In the skb_checksum_help function, a check for skb_has_shared_frag has been > added. > If the flag is not set, the skb buffer will remain non-linear, which is not > good. The Fixes tag indicates how far back the bug would trigger.
Re: [PATCH v2] net: missing check virtio
Thu, Jun 13, 2024 at 11:54:48AM CEST, are...@swemel.ru wrote:
>Two missing check in virtio_net_hdr_to_skb() allowed syzbot
>to crash kernels again
>
>1. After the skb_segment function the buffer may become non-linear
>(nr_frags != 0), but since the SKBTX_SHARED_FRAG flag is not set anywhere
>the __skb_linearize function will not be executed, then the buffer will
>remain non-linear. Then the condition (offset >= skb_headlen(skb))
>becomes true, which causes WARN_ON_ONCE in skb_checksum_help.
>
>2. The struct sk_buff and struct virtio_net_hdr members must be
>mathematically related.
>(gso_size) must be greater than (needed) otherwise WARN_ON_ONCE.
>(remainder) must be greater than (needed) otherwise WARN_ON_ONCE.
>(remainder) may be 0 if division is without remainder.
>
>offset+2 (4191) > skb_headlen() (1116)
>WARNING: CPU: 1 PID: 5084 at net/core/dev.c:3303 skb_checksum_help+0x5e2/0x740
>net/core/dev.c:3303
>Modules linked in:
>CPU: 1 PID: 5084 Comm: syz-executor336 Not tainted
>6.7.0-rc3-syzkaller-00014-gdf60cee26a2e #0
>Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google
>11/10/2023
>RIP: 0010:skb_checksum_help+0x5e2/0x740 net/core/dev.c:3303
>Code: 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 52 01 00 00 44 89 e2 2b
>53 74 4c 89 ee 48 c7 c7 40 57 e9 8b e8 af 8f dd f8 90 <0f> 0b 90 90 e9 87 fe
>ff ff e8 40 0f 6e f9 e9 4b fa ff ff 48 89 ef
>RSP: 0018:c90003a9f338 EFLAGS: 00010286
>RAX: RBX: 888025125780 RCX: 814db209
>RDX: 888015393b80 RSI: 814db216 RDI: 0001
>RBP: 8880251257f4 R08: 0001 R09:
>R10: R11: 0001 R12: 045c
>R13: 105f R14: 8880251257f0 R15: 105d
>FS: 55c24380() GS:8880b990() knlGS:
>CS: 0010 DS: ES: CR0: 80050033
>CR2: 2000f000 CR3: 23151000 CR4: 003506f0
>DR0: DR1: DR2:
>DR3: DR6: fffe0ff0 DR7: 0400
>Call Trace:
>
> ip_do_fragment+0xa1b/0x18b0 net/ipv4/ip_output.c:777
> ip_fragment.constprop.0+0x161/0x230 net/ipv4/ip_output.c:584
> ip_finish_output_gso net/ipv4/ip_output.c:286 [inline]
> __ip_finish_output net/ipv4/ip_output.c:308 [inline]
> __ip_finish_output+0x49c/0x650 net/ipv4/ip_output.c:295
> ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
> NF_HOOK_COND include/linux/netfilter.h:303 [inline]
> ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
> dst_output include/net/dst.h:451 [inline]
> ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:129
> iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82
> ipip6_tunnel_xmit net/ipv6/sit.c:1034 [inline]
> sit_tunnel_xmit+0xed2/0x28f0 net/ipv6/sit.c:1076
> __netdev_start_xmit include/linux/netdevice.h:4940 [inline]
> netdev_start_xmit include/linux/netdevice.h:4954 [inline]
> xmit_one net/core/dev.c:3545 [inline]
> dev_hard_start_xmit+0x13d/0x6d0 net/core/dev.c:3561
> __dev_queue_xmit+0x7c1/0x3d60 net/core/dev.c:4346
> dev_queue_xmit include/linux/netdevice.h:3134 [inline]
> packet_xmit+0x257/0x380 net/packet/af_packet.c:276
> packet_snd net/packet/af_packet.c:3087 [inline]
> packet_sendmsg+0x24ca/0x5240 net/packet/af_packet.c:3119
> sock_sendmsg_nosec net/socket.c:730 [inline]
> __sock_sendmsg+0xd5/0x180 net/socket.c:745
> __sys_sendto+0x255/0x340 net/socket.c:2190
> __do_sys_sendto net/socket.c:2202 [inline]
> __se_sys_sendto net/socket.c:2198 [inline]
> __x64_sys_sendto+0xe0/0x1b0 net/socket.c:2198
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0x6b
>
>Found by Linux Verification Center (linuxtesting.org) with Syzkaller
>
>Signed-off-by: Denis Arefev
Could you please provide "Fixes" blaming the commit which itroduced the
bug?
>---
> V1 -> V2: incorrect type in argument 2
> include/linux/virtio_net.h | 11 +++
> 1 file changed, 11 insertions(+)
>
>diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
>index 4dfa9b69ca8d..d1d7825318c3 100644
>--- a/include/linux/virtio_net.h
>+++ b/include/linux/virtio_net.h
>@@ -56,6 +56,7 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
> unsigned int thlen = 0;
> unsigned int p_off = 0;
> unsigned int ip_proto;
>+ u64 ret, remainder, gso_size;
>
> if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
>@@ -98,6 +99,16 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
> u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
> u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
>
>+ if (hdr->gso_size) {
>+ gso_size = __virtio16_to_cpu(little_endian,
>hdr->gso_size);
>+ ret = div64_u64_rem(skb->len, gso_size, );
>+
